[Olympiadis]

Nerys, I haven't posted here much but I like your thread and what you are doing so I wanted to jump in.

First I have to say I'd never before tried to imagine the sight of a 380 lb man in a tiny Metro pulling a small trailer. There's just something not so right about that.

I looked over your web-site as well. I suppose someone could have retarded your initial timing a bit to make up for the clogged EGR system. I like Harbor Freight, but I have to suggest you get a better quality timing light like a Craftsman dial-back style unit from Sears. In some cases it's worth going for the better quality, and IMO a timing light is one of those cases.

I don't want to come across as a know-it-all type, but I have done extensive testing myself back in the early 1990's starting in 1991. I want to say that you are definitely on the right track with your thinking.
I can't say that I like your testing methods as they are no-where near controlled enough to give reliable results, as far as testing procedures go. I do think that the trends you are seeing are in fact correct, and that you will continue to see them in the long-term barring other changes or outside forces.

In my area of Illinois back in 1991 some stations (namely the one I used) started offering the 10% Ethanol mixture, though you could still find E0 at many stations, making it very easy to run comparison testing.
I was doing both drag racing and fuel mileage testing at the time, and I first noticed problems on the drag-strip with reduced power, and need for adjusted tune. Most people did not notice the power difference because they were not tuned near the edge of maximum power. This is a big factor that hasn't been mentioned here.
My car was tuned to the lean limit at WOT and with the maximum spark-advance in each gear. This situation made any change in the fuel very noticeable and measurable. The actual density of the fuel with the E10 changed hardly at all, if any, but the energy content per mass changed, and the burn-speed in the chamber slowed down.
I wasn't happy about this at all, but I was even less happy with the effect it had on my Carter style AFB (aluminum four-barrel) carburetors that I was using on my cars at the time. The Ethanol would cause white crusty deposits and crystals to form on some surfaces of the carburetor to include the tiny air-bleed passages. Clogged air-bleeds cause serious driveability problems which was the red flag that led to the corrosion discovery. When using the E10 I had to tear down the carburetor for cleaning at least once per month. During tear down I also started noticing little pools of water in the bottom of the carburetor fuel bowls. The Ethanol was absorbing moisture from the air in the fuel tank and from the air above the carburetor fuel bowls, which are vented. Sometimes while taking off hard from a stop the water would be pulled back and cover the secondary fuel jets, which caused a sputtering for a few seconds until the water cleared the system.

While I had worked with both Ethanol and Methanol before and was fairly familiar with the effects, I had never used either for long-term street driving. Normal procedure for racers running alcohol is to either drain the system after racing, or to flush the system with gasoline - the gasoline being the best option because it cleans the alcohol away and also allows for much easier cold starting when ready to run again.

You would think, and I suppose most people do, that the small amount of Ethanol in E10 would have minimal effect in most cases of daily driving. Well, yes and no. In some vehicles it has little or no noticeable effect. It all depends on the individual set-up and the state of tune.

If the engine and/or driving conditions would favor a slower burning fuel, then one might break even or possibly profit by the results of E10. However, this would be very rare.

For example, if a racer was running a very conservative WOT tune of 12.0:1 AFR and 8* less than the maximum possible spark advance, then slowing the burn slightly is likely to go unnoticed. For a vehicle running 11.0:1 AFR, the change would probably not even be measurable with test equipment. Very rich AFRs burn so slow already that even changing the spark advance up to 10* (added) can often show no change in performance whatsoever. I have seen this in my own tests.

I also wanted to add that increasing fuel octane will also in most cases, slow the burn-speed in the chamber.

For best fuel mileage I can tell you from much experience that you do NOT want to increase your octane. Even low grade 87 octane is normally more than enough to cover the maximum load that your engine will see, even when going WOT up hills. For fuel economy style driving or hypermiling, you need nowhere near that high of an octane rating. In fact if you could find lower octane than 87, you would see improved mileage and your engine would perform better at lower RPM as well, which would skew your maximum fuel efficiency to a lower vehicle speed, as well as raise it across the board. Your only danger with low octane fuel is at certain high load levels, but is also dependent on intake air temperature and the metal temperature around the combustion chamber.

Even so, most modern engines have knock sensors that will detect spark knock and/or detonation and can adjust/retard up to 10* of spark advance (some systems can do more) to protect the engine. Failing all of that and you still have some occasional knock and you're at a relatively low throttle opening, your engine's VE is still so low that there is still very little chance of engine damage.

What I'm saying is that I don't recommend you trying to increase your octane with your washed gas. If anything your washed gas would already have reduced high-end volatiles and contain a bit of water, both of which will slow your burn down. Your testing will probably show you this eventually.
If anything I think you should try to increase the speed of your burn with your washed gasoline. There are several ways to do this, but one of the simplest is to just add a small bit of Acetone. In my experience wet-flow systems like the TBI or carburetor usually respond favorably to the Acetone, especially in cold conditions when slow burn is more of a noticeable problem. That's to say favorably in relation to burn-speed and fuel efficiency, and to exclude any side effects of the Acetone damaging rubber parts over the long-term. A warm-air intake would also have a similar effect of increasing burn speed by two mechanisms: the added heat and the better fuel vaporization and distribution. I'm just not so sure your combination would respond best with the added heat given your recent problems with EGR and spark advance. If you load your car with a lot of weight, the added heat of a WAI might cause you some knocking in the summer.

Still, I recommend you try and test different things and go where the results lead you, rather than from my advice.

My past testing had shown very consistently that, all things being equal, and with a naturally aspirated engine in good working order and in tune, the E10 will reduce fuel economy by varying degrees (percent). The differences were not directly related to the energy content difference by the way.
The factors that mattered most were things based around the changing burn-speed, like piston speed and load.

Burn-speed needs to match piston speed for an efficient transfer of energy.
In general, light cars with a lot of gear (more torque multiplication) were more lightly loaded (engine wise), and respond the most (negatively) to E10.
Heavy vehicles with highway gearing responded least (still negatively) to E10.

Also, carburetors and TBI (wet-flow systems) responded most (negatively) to the E10.
MPFI systems responded least (negatively) to the E10.

Other things that alter burn speed such as WAI and/or Acetone gave similar results but in reverse because of the increase in burn speed.
Lightly loaded vehicles with fast piston speed like fast burning mixtures.
Heavily loaded vehicles with a relatively slower piston speed like slower burning mixtures.
(don't confuse piston speed with RPM, they are not identical terms)
- and in all cases E0 produced the best results for fuel mileage.

A couple of exceptions were noted when the vehicle was not running in perfect order due to high mileage (lost compression), or misfiring cylinders due to weak ignition or faulty plugs. A car with a faulty tune (even with MPFI) would respond very negatively to the addition of E10 or anything that would slow the burn rate. Apparently the slower burn would increase the rate of misfires, and/or the alcohol would push (decrease) the misfire threshold.

Also, an engine tuned to the edge, as in the lean-limit (open-loop tune), would show a very pronounced negative effect from the E10.

I have friends who race with boosted MPFI systems (turbocharged) that run on high octane race gasoline, Methanol, Ethanol, E85, and/or gasoline mixed with Toluene or Xylene. Highly loaded turbocharged systems have high intake air temperature and naturally have a very high burn-rate when loaded, even when running very fuel-rich AFRs. They see a very significant power increase when running a fuel that will slow the burn rate and resist detonation under load. Their part-throttle and fuel mileage leave a LOT to be desired though. They experience regular spark-plug fouling and engine oil contamination when using the slow burning fuels for street driving. A highly tuned MPFI system with E85 is streetable, but still quite inefficient.

I prefer to use OLSD (open-loop speed-density) tuned engines as my concrete baseline and yardstick for testing as the results are dead-on consistent, and I don't have to fool with keeping track of closed-loop adjustments to fuel trims as the ECM tries to make up for whatever change you are testing. I test closed-loop systems as well of course, but I am more hesitant to trust their reliability without extra testing.

I have talked a lot about testing, so let me say a little about my methods.
I use multiple test loops of a 60 mile highway route for highway testing to get average of 3 loops. I also have a stop-n-go route that (I rarely use) I do ten laps/loops, and average two or three sets of ten loops. I test between 0100 and 0500 in the mornings and use a Davis weather computer to keep track of conditions. My filling method has always been to fill to a viseable spot in the fuel filler neck while sitting in the exact same spot at the same gas pump. I have found this the most reliable besides using a custom fuel-cell (tank) with a narrow filler tube (like a beaker top).
I have used various things for scanning & datalogging: Diacom, LS1scan, EFIlilve, TunerProRT, TunerCat, WinALDL, etc...
I use an Innovate wide-band O2 sensor to track AFR.
I use an older style Vericom2000 accelerometer for power testing (racing).

I've been doing this for a long time and I trust my testing methods after revising them slightly over the years to be more thorough, but I always suggest that people get their own test equipment and do their own testing.
Different cars and set-ups can and do react differently, and the more testing being done out there, the more little discoveries will be made.

Sorry for the long post.